1. Marine Climate Case Study
Miranda Homes
NAHB Research Center
Residential Building Energy Efficiency Meeting
July 2010

2. Summary
 Details
 Unique aspects
 Construction
 Energy Analysis
 Energy Monitoring
 Comparison
p. 2

3. Project Location
p. 3

4. Miranda Homes • Harbor View
Clackamas, OR
p. 4

5. Miranda Homes • Harbor View
Clackamas, OR
 Harbor View Model
 Harbor Home 1
 Marine Climate
 1,569 sqft
 Crawlspace foundation
 Panelized Walls
 Steel framed homes
 Affordable, ↓cycle time
p. 5

6. Details
Miranda Homes • Harbor Home 1
System Description Specifications
Foundation Unvented Crawlspace R-23 (ICF)
Panelized Walls Advanced steel framing (2 x 6)
Continuous Sheathing OSB
Walls
Spray Foam Insulation R-24
Exterior Rigid Foam Insulation R-4.4
Roof / Attic Spray Foam R-45 unvented attic
Windows High Performance Windows Low-e; U = 0.30 / SHGC = 0.31
Electric Heat Pump
Heating System
Located in Conditioned Space 8.5 HSPF
Central Unit
Cooling System 15 SEER
Located in Conditioned Space
100% interior
Ducts Located in Conditioned Space
5% leakage to exterior (28.4 cfm25)
Ventilation Fresh Air Ventilation 38 cfm exhaust ventilation
Water Heater Electric Hot Water Heater 0.92 EF electric tank
Lighting 75% fluorescent CFL and permanent
Appliances Energy Star (where supplied)
Air Infiltration Air Sealing Details 2.31 ACH50
p. 6

7. Construction Process
Miranda Homes • Harbor Home 1
 Manufacture steel studs
 Panelize Walls
 Steel studs
 OSB
 Exterior rigid foam
 Set walls on foundation
 ICF
 Conditioned crawl
 Manufacture roof trusses
 All SPF insulation AG
p. 7

8. Panelized 2x6 Walls
Miranda Homes • Harbor Home 1
p. 8

9. Wall Interior
Miranda Homes • Harbor Home 1
p. 9

10. Spray Foam Applied
Miranda Homes • Harbor Home 1
p. 10

11. Ducts & HVAC
Miranda Homes • Harbor Home 1
p. 11

12. Lighting & Appliances
Miranda Homes • Harbor Home 1
p. 12

13. Energy Analysis
Miranda Homes • Harbor Home 1
House Feature Typical Construction Miranda Homes Design
Floor Area 1569 square feet, single story 1569 square feet, single story
Window area 252 square feet 252 square feet
Foundation Crawlspace, R-30 floor Crawlspace, conditioned, R-23
Bathrooms 2 2
Ceiling Flat ceiling, vented attic R38 Unvented attic, R-45
Roof framing Wood Metal
Wall framing Wood, 2x6, advanced framing Metal, 2x6, 20% framing factor1
Wall insulation R-19 cavity R-24 cavity, R-4.35 exterior
Windows U-0.35/0.4 SHGC U-0.30/0.31 SHGC
Infiltration 0.35 ACHnat2 0.122 ACHnat
Ventilation None 100 CFM, runtime 20% minimum
Cooling System Efficiency 13 SEER 15.5 SEER
Heating System Efficiency 7.7 HSPF 8.5 HSPF
Duct Location Interior/Crawlspace, insulated Interior
Duct sealing Assumed air-tight As measured
Temperature Set-point 76 Cooling – 71 Heating 76 Cooling – 71 Heating
Lighting Energy 2,064 kWh/yr 1,183 kWh/year
Appliances and Plug 4,399 kWh/yr 4,399 kWh/yr
1 Framing system optimized using panelization software and engineered components
2 Based on ASHRAE 62.2 minimum infiltration before mechanical ventilation required
p. 13

14. Energy Analysis
Miranda Homes • Harbor Home 1
 46% Energy
Savings
 Over BA
Benchmark
 HERS Index
 69 (w/out PV)
p. 14

15. Monitoring
Miranda Homes • Harbor Home 1
 Instruments were installed to
monitor:
 Indoor and outdoor
temperatures
 Whole-house electricity use
 Heating system electricity use
 Water heating electricity use
 Duct supply and ventilation
temperatures
p. 15

16. Weather Data Comparison
Heating Degree Days
 Temperature difference
between indoors & out
 During monitoring
period
 15% fewer heating
degree days
 2,941 HDD monitored
 3,468 HDD simulations
p. 16

17. Weather Data Comparison
Daily Temperature Profile
p. 17

18. Temperature Data
Daily Average Temperature Profile
p. 18

19. Temperature Data Profile
 Measured Temp
 Daily Average: ≈ 2°F higher
than TMY3
 Average Min: ≈ 1°F higher
 Average Max: ≈ 3°F higher
 Average Interior: within 1°F
 Daily Interior temperature
range is larger (over 2°F
during heating season)
p. 19

20. Monitored Data
Miranda Homes • Harbor Home 1
p. 20

21. Performance Comparison
Simulated vs. Measured for Period
Difference between
Simulation Measured
Performance Metric Unit Measured and
Data Data
Simulated Data
Average Outdoor Temperature 48.3 49.0 °F +0.7 °F
Average Daily Maximum
56.6 60.1 °F +3.5 °F
Temperature
Average Daily Minimum
39.9 41.0 °F +1.1 °F
Temperature
Average Indoor Temperature 71.7 70.8 °F -0.9 °F
Heating Energy Use 2,646 2,319 kWh -12.4%
Hot Water Energy Use 1,819 1,427 kWh -21.6%
Appliance and Lighting Energy
3,179 2,692 kWh -15.3%
Use
Whole House Energy Use 7,644 6,438 kWh -15.8%
p. 21

22. Heating Comparison
Electric Energy & Temperature
p. 22

23. Heating Comparison
Heating System Performance
p. 23

24. Company Structure
Miranda Homes • Harbor Home 1
 Miranda Homes staff
construct homes
 Vertically integrated
 Minimize construction time
 Minimize callbacks
 Integrated Quality
Management
p. 24

25. Conclusions & Next Steps
Miranda Homes • Harbor Home 1
 Energy efficiency  Simulation model
enhancements have adequately predicts
enabled successful energy usage
use of steel framing  Further analysis is
 Monitored data is needed using annual
fairly well matched data
with predicted data  Based on data further
& confirms savings enhancements may
be identified
p. 25

26. Questions?
Amber Wood
Program Manager, Energy Efficiency
NAHB Research Center
301-430-6309
awood@nahbrc.com
p. 26